Good environment art takes a lot of attention to detail. It's relatively easy slap a quick photo-sourced texture onto an object and call it done, but using this method is very rarely going to generate a satisfactory result.
Professional production work-flows don't always allow for hands on detailing of every surface in an image or frame, however a little bit of work can go a long way, and as high-poly to low-poly sculpting pipelines become more and streamlined, using software like Zbrush and Mudbox in production settings has slowly but surely become the norm.
Knowing how to efficiently sculpt various wood pieces (beams, planks, panels, etc) is massively important in game-art because they're one of the single most ubiquitous accent pieces used in environment design.
They're also relatively straightforward and incredibly re-usable, which makes them a perfect addition to your personal asset library.
So let's do it! In the remainder of the article, we'll take a look at how to approach a simple wood beam in Zbrush, from basemesh to brushes, texturing, and detailing.
Step 1 - Basemesh
For a wood piece like the one we're working on, the basemesh should be as simple as an elongated cube with even (square) subdivisions. It's important to think about how your basemesh will subdivide in Zbush so that there are no surprises (like insufficient resolution) when you begin sculpting or detailing.
Follow these steps to create the basemesh:
- Create a cube with no subdivisions. Scale it on the x-axis it until you have a rectangular shape suitable for a heavy wood beam.
- Duplicate the cube. One of these will be the low-poly cage that we'll bake our texture/normal maps onto and one will be the high-poly mesh that we'll sculpt on. Re-name them accordingly (something like wood_LP and wood_HP will work).
We won't need the low-poly mesh until much later in the process, so either hide it or place it on an invisible layer.
- Next we need to set up our high-poly mesh for sculpting. Using the insert edge loop tool, add resolution in the height, width, and length. The number of subdivisions you'll want to add will depend on the shape of your mesh, but we added two edge loops on the width and height, and twenty edge loops along the length. As you can see in the picture above, our faces are roughly square in shape—this is what you should be aiming for.
- That's it for the basemesh! Save your scene, select the cube, then go to File → Export Selection → and export the cube as an .obj file. If .obj doesn't appear as an option, you'll need to reload the plugin.
Step 2 - Weather the Edges
- Import your cube into Zbrush. With an organic sculpt you'd want to start sculpting at a low resolution, and only subdivide when you've pushed the silhouette as far as possible at your current level.
However, in this case our silhouette is pretty much set—most of what we're doing is detailing so we want to bring the mesh resolution up into the 1-3 million poly range.
Go into the geometry menu and subdivide a few times. To prevent your mesh from becoming “soft,” perform your first two subdivisions with the smooth modifier turned off. This will preserve your hard edges.
- We need to add some weathering to the edges of the cube to add some visual interest.
No piece of wood in the world has perfectly sharp edges. If you look at pictures of wooden beams (particularly in timber-frame architecture), there are usually nicks, dents, and even whole chunks missing along the edges.
In sculpting for game-art, exaggeration is almost always better than restraint. Most wood beams in the real world don't have visible weathering along their entire length, but I like to go over the top. Adding a slight bevel to the entire edge will make for a better normal map, and help the asset catch the light-better in-game.
- Using the Trim Dynamic Brush with the z-intensity at 30-40, knock down the edges of the cube to your liking.
Make sure you use a variety of radius sizes on your brush so that the surface doesn't become too uniform. Be sure to keep some sections sharp—you don't want your beam to read “too-soft”, like a piece of clay.